1. Field of the Invention
This invention relates to high-speed printers. More particularly, it relates to a printer having multiple bins into which items are sorted after printing.
2. Description of the Prior Art
U.S. Pat. No. 6,241,460 to the present inventor, entitled: “Offset Sorter For Envelopes,” discloses a sorter that separates bundles of items to be mailed from one another. A first wall is extended as a first bundle of items is received within a bin so that the leading edge of each item is aligned with the first wall. The first wall retracts when a bundle has been completed and the items of the next bundle travel a little further along their path of travel until they encounter a second wall. The leading edge of each item in the second bundle thus aligns with the second wall. After that bundle has been completed, the first wall is again extended. Thus, each bundle is physically staggered from the bundle in front of it or behind it so that a worker can easily separate the bundles from one another. In most cases, the worker will insert a separator or divider sheet between contiguous bundles to divide them from one another.
After the separator/divider sheets have been inserted, the worker transfers all of the bundles in a bin to a postal container for delivery to the postal service. The worker must also maintain a steady flow of envelopes into the hopper of the machine. Thus, the worker is busy keeping the hopper full and emptying the bin as it is filled.
It would therefore be advantageous to provide a machine having multiple bins so that a second bin can begin to fill while items are being manually removed from a first full bin. Where a machine operates at a very high speed, it would be advantageous to add a third, a fourth, and even higher numbers of bins so that the machine would not need to operate at a slow speed just to facilitate manual removal of items from the bins.
It would also be advantageous if automatic means could be provided to insert a divider sheet or other bundle-dividing marker between contiguous bundles to lower the effort required by the machine operator and to reduce the number of mistakes that an operator may make when manually inserting such divider sheets.
Another problem with high-speed machines is that envelopes and other items have to slow down when they enter into a nip (defined by a pair of opposing rollers). When a leading envelope slows down upon encountering a nip, the leading end of a trailing envelope collides with the trailing end of the leading envelope.
In prior art machines, the nip rollers do not rotate during a time that multiple envelopes are accumulating upstream of the nip. Accordingly, the respective leading ends of all of the envelopes or other items are aligned with one another as such items accumulate. When a predetermined number of envelopes have accumulated, forming a bundle, the nip rollers are activated and the bundle of envelopes is moved through the nip to a collection station or bin. As soon as the bundle has passed through the nip, the rollers stop turning and envelopes again begin to accumulate.
However, there is a need for a high-speed machine where envelopes or other items do not accumulate upstream of a non-rotating nip. In other words, there is a need for a continuously rotating nip where no accumulation occurs and each envelope approaching a nip is carried therethrough at a high rate of speed. In such a machine, the leading ends of the items would be staggered, i.e., shingled with respect to one another. By keeping the nip rollers rotating substantially at all times, the quantity of items that could be handled would significantly increase.
An item such as an envelope will slow down when its leading end encounters a nip, even when the nip is rotating. Accordingly, the leading end of a trailing envelope will collide with collide with the trailing end of the leading envelope as aforesaid. This problem, heretofore unsolved, prevents operation of very high speed printing machines having rotating nips. Instead, as mentioned above, the machines must be equipped with nips that do not rotate during bundle-formation. Even when so configured, the speed with which a bundle may be formed is limited by the fact that the respective leading ends of trailing items will collide with the respective trailing ends of leading items.
Accordingly, there is a need for a structure that enables a leading envelope to slow down upon encountering a nip, but which moves the trailing end of such envelope out of the path of travel of a trailing envelope so that the leading end of the trailing envelope does not contact the trailing end of the leading envelope.
Such a structure would speed up the formation of a bundle of items in a machine of the type where envelopes or other items are accumulated in a bundle before passing through a nip.
Such a structure would also facilitate operation of a machine having rotating nips where a lead envelope slows down upon encountering a nip but where no envelopes are accumulated in a bundle upstream of the nip. The trailing envelope would then overlie a large part of the leading envelope in the aforementioned configuration known as “shingling.” When two envelopes are in shingled relation to one another, the trailing envelope is disposed in overlying relation to the leading envelope and the leading end of the trailing envelope is disposed in trailing relation to the leading end of the leading envelope. The amount of shingling may vary. For example, there may be one inch of shingling, two inches, two and one-half inches, and so on.
One drawback associated with such shingling is that a trailing envelope may be too far behind a leading envelope to create the proper amount of shingling. There is a need, therefore, for a machine that can detect a gap between envelopes of other items that exceeds a predetermined gap, and that can reduce that gap as needed so that proper shingling may occur.
Very high-speed printing machines also cause problems with ink-drying. The ink on an envelope or other item leaving a printer may not have sufficient time to dry before entering a sorter that directs the items to various bins.
Thus there is a need for a high-speed machine that efficiently dries the ink on items prior to entry of such items into a sorter.
However, in view of the prior art taken as a whole at the time the present invention was made, it was not obvious to those of ordinary skill how the identified needs could be met.